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What Makes Up a Roof? The Various Layers Explained

A roof is just the top of a house, right? Nope! In fact, a roof is a complex system comprised of various layers that work together to protect your home from outdoor elements. Should one of those essential layers start to fail, it can affect the integrity of the entire roof. The roofing professionals at Performance Roofing explain the various layers that comprise a roof and the function each one plays.

The Different Layers of a Roof from Bottom to Top


Typically constructed of plywood or plank lumber, this roof layer is installed over the framing and provides structure by tying the trusses and joists together. It is additionally the foundation upon which the roofing system is attached.


Traditionally comprised of organic felt soaked in asphalt for waterproofing, roofing underlayment has transitioned over the past few years more commonly to a synthetic material that can be compared to a heavy-duty tarp material. While its primary function is to keep the structure temporarily dry until the application of the final roofing material, it also provides an extra layer of protection between the shingles and the decking in case your roofing material is blown off in a major storm event. Upgraded underlayments also include a self-adhering underlayment that is adhered directly to the deck. While this has a higher up-front investment, it will provide insurance credits to lower your annual insurance premiums.

Leak Barriers

This component is a self-adhering, water-proof, and self-sealing membrane that is applied to the roof deck in valleys, around penetrations, and at flashing transitions for additional protection. It can also be used as an upgraded underlayment in low slope areas or as described above, as a complete upgraded underlayment to protect against water infiltration from heavy rain.


Flashing is a thin metal typically constructed of galvanized steel, aluminum, or copper that is used to direct water away from the area where the vertical walls transition to the roofing system. This detail can be found at sidewalls, headwalls, around chimneys, or around skylights. Because flashing can be one of the first layers to fail if installed improperly, it should be inspected regularly to ensure your home has a watertight seal.

Starter Strip

These specialized shingles line the edge of the roof and start the application of a shingle roofing system. They are installed after the decking and underlayment have been applied. The main purpose of a starter strip is to seal the edge of your roof, which significantly increases the roof’s ability to withstand powerful winds and heavy rain.


Shingles are the exposed layer of a common roofing system and are traditionally comprised of a fiberglass mat surrounded by asphalt and granules for protection from the elements. Without shingles, the structure would be pummeled and unprotected. They are the first defense against the elements and carry the aesthetic value as well.

Ridge Caps

Ridge caps are specialized, accessory shingles installed along the hips and ridgeline of a sloped roof that prevent rain from entering your home. They also finish the look of the roof by creating a tightly sealed joint along the two sides.

Performance Roofing – Orlando’s Premier Roofing Specialists

At Performance Roofing, we provide quality roofing services! Whether you need a roof repair or replacement, we will take care of your roofing needs. Contact our roofing specialists today at 407.783.8646 for a FREE inspection.